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Blink and You'll Miss It
Male mosquitofish can complete mating in under one second — among the fastest sex acts in the animal kingdom.
Mosquitofish
Gambusia affinis
These tiny fish are named for eating mosquito larvae, but they're also known for incredibly fast mating.
Vital Stats
🏷️ TypeFish (live-bearer)
🌍 Found InOriginally southeastern USA, now invasive worldwide — ponds, streams, ditches
📏 SizeFemales: 4-7cm | Males: 2.5-4cm
⏳ Lifespan1-2 years
🔞 Sexual Maturity4-8 weeks
💕 Mating SystemAggressive — males attempt to mate every few minutes
📅 Mating SeasonYear-round in warm climates; spring-fall in temperate zones
🤰 Gestation21-28 days (internal development)
👶 Offspring10-80 live fry per brood, 3-4 broods per year
🍆 Penis Size5.0 mm
⏱️ Sex Duration500 milliseconds
🔬 Notable AnatomyMales have modified anal fin (gonopodium) for internal fertilization; mating takes milliseconds
⚖️ Sexual DimorphismFemales much larger; males have gonopodium